Our general aim is to discover how the brain processes visual information, how neural activity is related to visual perception, and how visual processing interacts with other brain systems underlying cognition. Our specific aim is to elucidate how pigeons recognize and conceptualize visual stimuli. By studying the pigeon-a highly visual animal which can readily learn, but which does not have language or a mammalian neocortex and whose history can be carefully controlled and systematically varied-the processes of visual recognition and conceptualization may be more quickly and readily discovered. If the visual discrimination behavior of pigeons resembles that of humans, then the processes of conceptualization may be mediated by common neurobiological mechanisms which do not depend on linguistic competence or the human brain. The pigeon may become a powerful model system for both behavioral and biological studies of complex visual processing. Our proposal aims to see whether the perceptual processes of recognition and conceptualization are similar in humans and pigeons. Pigeons will be trained with several different operant conditioning procedures to discriminate line drawings and computer renderings of natural and artificial stimuli. The pigeons will later be tested with stimuli that: (1) degrade the training stimuli, (2) rearrange its parts, and (3) rotate the image in depth. These test stimuli produce highly specific effects in humans, which encourage the idea that object recognition is mediated by a structural description specifying a neural representation of the object's parts and the relations among those parts. If people and pigeons similarly process these various visual stimuli, then the results of our experiments with pigeons should parallel those with people. Empirical convergence would attest to the economy of nature and to the superfluity of language for visual recognition and conceptualization. Empirical divergence would imply that different neurobiological or linguistic mechanisms mediate visual recognition and conceptualization in people and pigeons. In either case, the results of this research project should shed considerable light on the basic mechanisms of visual recognition and conceptualization. Beyond the scientific significance of our proposed research, its health relevancy is considerable. Developing sound animal models of object recognition and conceptualization might better enable us to understand the behavioral and biological mechanisms of the human visual system in both health and disease. Effective animal models may also help pave the way for devising nonverbal diagnostic tests for assessing visual performance. In addition, comparing how pigeons and people recognize objects could provide new insights for computer and cognitive scientists to construct artificial devices which can recognize complex stimuli in the real world. Discovering how different biological systems accomplish the same adaptive feat might greatly help those attempting to create different artificial and prosthetic systems of object recognition. PUBLIC HEALTH RELEVANCE: The development of animal models of object recognition and visual conceptualization might better enable us to understand the behavioral and biological mechanisms of the human visual system in both health and disease. Effective animal models may also help pave the way for devising practical diagnostic tests for assessing visual performance;particularly important here is the fact that verbal behavior need not participate in such performance assessments, making nonverbal tests especially useful with infants, young children, and clinical populations. Our results should also advance our understanding of how the visual system develops and how to promote its regeneration after disease or injury.